Unixcop published a guide about installing LightZone on Ubuntu 20.04.

How To Install LightZone on Ubuntu 20.04

In this article, we will show you how to install LightZone on Ubuntu systems LightZone is a free, open-source digital photo editor software application. It was originally developed as commercial software by the now-defunct Light Crafts. Its main purpose is to handle the workflow, including non-destructive editing when handling images in various RAW formats. It is comparable to Adobe Lightroom. LightZone edits both RAW and JPEG format images. 

How To Install LightZone on Ubuntu 20.04 - Unix / Linux the admins Tutorials